Use of HardyDisk™ AST Delafloxacin 5μg (DLX5) , for in vitro agar diffusion susceptibility testing is indicated when there is need to determine the susceptibility of bacteria to Delafloxacin. The concentration of Delafloxacin 5pg (DLXS), has been shown to be active against susceptible isolates of the following microorganisms both in vitro and in clinical infections: Staphylococcus aureus (including methicillin-resistant and methicillin-sensitive strains) Staphylococcus haemolyticus Streptococcus pvogenes Streptococcus anginosus Group (including S. anginosus, S. intermedius, S. constellatus) Enterococcus faecalis Escherichia coli Klebsiella pneumoniae Enterobacter cloacae Pseudomonas aeruginosa The concentration of Delafloxacin 5ug (DLXS), has been shown to be active against susceptible isolates of the following microorganisms for in vitro use: Streptococcus dvsgalactiae Enterobacter aerogenes Haemophilus parainfluenzae Klebsiella oxytoca Proteus mirabilis HardyDisk™ AST Disks are used for semi-quantitative in vitro susceptibility testing by the agar diffusion test procedure (Kirby-Bauer) of rapidly growing and certain fastidious bacterial pathogens. Standardized methods for agar diffusion testing have been described for Enterobacteriaceae, Staphylococcus spp., Acinetobacter spp., Listeria monocytogenes, Enterococcus spp., and by modified procedures, Haemophilus spp., Neisseria gonorrhoeae, N. meningitidis and Streptococcus spp., including Streptococcus pneumoniae.
Device Story
HardyDisk AST Delafloxacin 5μg (DLX5) consists of 6-mm diameter filter paper disks impregnated with 5μg of Delafloxacin. Used in clinical microbiology laboratories for semi-quantitative in vitro antimicrobial susceptibility testing via the Kirby-Bauer agar diffusion method. Laboratory personnel inoculate agar plates with bacterial isolates, apply disks, and incubate. Following incubation, the user measures the zone of inhibition diameter around the disk. These measurements are compared against established FDA interpretive criteria to categorize the isolate as susceptible, intermediate, or resistant to Delafloxacin. This information assists clinicians in selecting appropriate antibiotic therapy for patients with bacterial infections.
Clinical Evidence
No clinical data. Performance characteristics were established based on studies evaluated by FDA/CDER at the time of Delafloxacin pharmaceutical approval.
Technological Characteristics
Paper disk impregnated with 5 ug of Delafloxacin. Operates via passive diffusion in agar medium (Kirby-Bauer method).
Indications for Use
Indicated for in vitro agar diffusion susceptibility testing to determine bacterial susceptibility to Delafloxacin. Active against Staphylococcus aureus, S. haemolyticus, Streptococcus pyogenes, S. anginosus Group, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, S. dysgalactiae, Enterobacter aerogenes, Haemophilus parainfluenzae, Klebsiella oxytoca, and Proteus mirabilis.
Regulatory Classification
Identification
An antimicrobial susceptibility test disc is a device that consists of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc-broth elution technique the in vitro susceptibility of most clinically important bacterial pathogens to antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly measuring the magnitude of a zone of bacterial inhibition around the disc on an agar surface. The disc-broth elution technique is associated with an automated rapid susceptibility test system and employs a fluid medium in which susceptibility is ascertained by photometrically measuring changes in bacterial growth resulting when antimicrobial material is eluted from the disc into the fluid medium. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.
Submission Summary (Full Text)
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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
ASSAY ONLY TEMPLATE
A. 510(k) Number:
K171975
B. Purpose for Submission:
Addition of Delafloxacin Antimicrobial Susceptibility Test Disk
C. Measurand:
Delafloxacin, 5μg
D. Type of Test:
Antimicrobial Susceptibility Test Disks
E. Applicant:
Hardy Diagnostics
F. Proprietary and Established Names:
HardyDisk AST Delafloxacin 5μg (DLX5)
G. Regulatory Information:
1. Regulation section:
21 CFR 866.1620 Antimicrobial Susceptibility Test Disc
2. Classification:
Class II
3. Product code:
JTN – Susceptibility Test Disc, Antimicrobial
4. Panel:
83 - Microbiology
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H. Intended Use:
1. Intended use(s):
HardyDisk AST Disks are used for semi-quantitative *in vitro* susceptibility testing by the agar diffusion test procedure (Kirby-Bauer) of rapidly growing and certain fastidious bacterial pathogens. Standardized methods for agar diffusion testing have been described for *Enterobacteriaceae*, *Staphylococcus* spp., *Pseudomonas* spp., *Acinetobacter* spp., *Listeria monocytogenes*, *Enterococcus* spp., and by modified procedures, *Haemophilus* spp., *Neisseria gonorrhoeae*, *N. meningitidis* and *Streptococcus* spp. including *Streptococcus pneumoniae*.
2. Indication(s) for use:
Use of HardyDisk AST Delafloxacin 5 µg (DLX5), for *in vitro* agar diffusion susceptibility testing is indicated when there is need to determine the susceptibility of bacteria to Delafloxacin.
The concentration of Delafloxacin 5 µg (DLX5), has been shown to be active against susceptible isolates of the following microorganisms both *in vitro* and in clinical infections:
- *Staphylococcus aureus* (including methicillin-resistant and methicillin-sensitive strains)
- *Staphylococcus haemolyticus*
- *Streptococcus pyogenes*
- *Streptococcus anginosus* Group (including *S. anginosus*, *S. intermedius*, *S. constellatus*)
- *Enterococcus faecalis*
- *Escherichia coli*
- *Klebsiella pneumoniae*
- *Enterobacter cloacae*
- *Pseudomonas aeruginosa*
The concentration of Delafloxacin 5 µg (DLX5), has been shown to be active against susceptible isolates of the following microorganisms for *in vitro* use:
- *Streptococcus dysgalactiae*
- *Enterobacter aerogenes*
- *Haemophilus parainfluenzae*
- *Klebsiella oxytoca*
- *Proteus mirabilis*
HardyDisk AST Disks are used for semi-quantitative *in vitro* susceptibility testing by the agar diffusion test procedure (Kirby-Bauer) of rapidly growing and certain fastidious bacterial pathogens. Standardized methods for agar diffusion testing have been described for *Enterobacteriaceae*, *Staphylococcus* spp., *Pseudomonas* spp., *Acinetobacter* spp., *Listeria monocytogenes*, *Enterococcus* spp., and by modified procedures, *Haemophilus* spp., *Neisseria gonorrhoeae*, *N. meningitidis* and *Streptococcus* spp., including *Streptococcus pneumoniae*.
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3. Special conditions for use statement(s):
For prescription use only
There are no non-susceptible (i.e., intermediate and resistant) breakpoints established for *Streptococcus pyogenes* and *Streptococcus anginosus* Group. The following statement is added in the labeling as a footnote for these two organism groups:
The current absence of resistant isolates precludes defining any results other than "Susceptible". Isolates yielding results other than "Susceptible" should be submitted to a reference laboratory for further testing.
Regarding resistance mechanisms for fluoroquinolones, the following statement is added in the labeling as a footnote:
The performance of HardyDisk AST Delafloxacin 5μg (DLX5) is unknown for organisms with the following fluoroquinolones resistance mechanisms: topoisomerase IV and DNA gyrase Quinolone-Resistant Determining Regions (QRDRs) or altered efflux"
Due to lack of interpretative criteria for *Staphylococcus lugdunensis*, the following statement is added in the labeling as a footnote:
"Staphylococcus lugdunensis is an indicated organism in the FDA approved pharmaceutical labeling but it is not included in this device labeling since no interpretive criteria have been established for this organism."
4. Special instrument requirements:
Not Applicable
I. Device Description:
The HardyDisk AST Disks utilize 6-mm diameter white filter paper disks. The disks are prepared by impregnating absorbent paper with a known concentration of 5μg Delafloxacin. The disks are marked with the code DLX5 on both sides.
HardyDisk AST Disks are supplied in plastic cartridges containing 50 disks each. They are also packaged as one cartridge per vial with desiccant or five cartridges per vial with desiccant.
J. Substantial Equivalence Information:
1. Predicate device name(s):
HardyDisk Tigecycline 15μg
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2. Predicate $510(\mathrm{k})$ number(s):
K062245
3. Comparison with predicate:
Table 1: Comparison with Predicate Device
| Similarities | | |
| --- | --- | --- |
| Item | Device(K171975) | Predicate(K062245) |
| Test Method | Antimicrobial Susceptibility testing using paper discs impregnated with an antimicrobial agent | Same |
| Intended Use | Antimicrobial Susceptibility Test Disks are used for in vitro susceptibility testing by standardized agar diffusion test procedures. | Same |
| Methodology | Kirby-Bauer Disk Diffusion Susceptibility Test Protocol. Require the user to determine categorical interpretations (S/I/R) using the measured zone diameters. | Same |
| Inoculum | Prepared from pure isolated colonies to match the turbidity equivalent of a 0.5 McFarland in Tryptic Soy Broth. | Same |
| Inoculum Method | Dip a sterile swab into the prepared inoculum, and streak an appropriate agar plate's surface three times. Add the disks impregnated with the antimicrobial agent to the surface of the plate. Incubate the plate agar side up in a 35 +/- 2°C incubator for 18-24 hours. | Same |
| Interpretation | The user will interpret the zone diameters according established interpretive criteria for the drug. | Same |
| Differences | | |
| Item | Device | Predicate |
| Product Name | HardyDisk AST Delafloxacin 5μg (DLX5) | HardyDisk Tigecycline |
| Antibiotic | Delafloxacin | Tigecycline |
| Concentration | 5 μg | 15μg |
# K. Standard/Guidance Document Referenced (if applicable):
CLSI M02-A12, Performance Standards for Antimicrobial Disk Susceptibility Tests; Approved Standard- Twelfth Edition
CLSI M100-S27, Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Seventh Informational Supplement
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L. Test Principle:
The HardyDisk AST Disks is based on the agar diffusion (Kirby-Bauer) methodology. It utilizes dried filter paper disks impregnated with known concentrations of antimicrobial agents that are placed onto the test medium surface. Mueller Hinton agar is recommended for agar diffusion testing of non-fastidious organisms and Mueller Hinton with 5% Sheep Blood for Streptococcus spp. Three to five similar colonies are transferred to 4-5 mL of a suitable broth medium. The broth is incubated at 35°C for 2-6 hours to develop a turbidity that exceeds or is equivalent to a 0.5 McFarland standard. Alternatively, a direct broth or saline suspension of colonies may be prepared from an overnight culture. The final inoculum density should be equivalent to a 0.5 McFarland turbidity standard. The inoculum density may also be standardized photometrically.
Within 15 minutes of inoculum preparation, the Mueller Hinton agar is streaked with an inoculated swab to obtain an even inoculation. Disks are aseptically placed onto the agar surface with a disk dispenser and the disks are pressed down with a sterile needle or forceps to make contact with the agar surface. Agar plates are incubated in an ambient air incubator at 35±2°C for 16-18 hours. Fastidious organisms are tested using appropriate media incubated in an atmosphere enriched with 5% CO₂, as recommended in the CLSI M02 approved standard document.
After incubation the agar medium is examined for zone of inhibition around the disks. The zones of inhibition are measured to the nearest millimeter and compared against recognized zone size ranges for the antimicrobial agent being tested.
M. Performance Characteristics (if/when applicable):
Descriptive characteristics were sufficient for this Delafloxacin disk. The studies evaluated by FDA/CDER at the time of Delafloxacin approval were used for this review.
1. Analytical performance:
a. Precision/Reproducibility:
Not applicable
b. Linearity/assay reportable range:
Not applicable
c. Traceability, Stability, Expected values (controls, calibrators, or methods):
Not applicable
d. Detection limit:
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Not applicable
e. Analytical specificity:
Not applicable
f. Assay cut-off:
Not applicable
2. Comparison studies:
a. Method comparison with predicate device:
Not applicable
b. Matrix comparison:
Not applicable
3. Clinical studies:
a. Clinical Sensitivity:
Not applicable
b. Clinical specificity:
Not applicable
c. Other clinical supportive data (when a. and b. are not applicable):
Not applicable
4. Clinical cut-off:
Not applicable
5. Expected values/Reference range:
The interpretative criteria recommended by the FDA/CDER in the approved pharmaceutical drug package insert are shown in Table 2.
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Table 2: FDA Interpretative Criteria for Delafloxacin
| Indications For Use Organism(s) | Interpretative Criteria | | |
| --- | --- | --- | --- |
| | Zone Diameter (mm) | | |
| | R | I | S |
| Staphylococcus aureus(methicillin-resistant and methicillin susceptible isolates) | ≤19 | 20-22 | ≥23 |
| Staphylococcus haemolyticus | ≤20 | 21-23 | ≥24 |
| Streptococcus pyogenes\(^a\) | -- | -- | ≥20 |
| Streptococcus anginosus Group\(^a\) (S. anginosus, S. intermedius, S. constellatus) | -- | -- | ≥25 |
| Enterococcus faecalis | ≤18 | 19-20 | ≥21 |
| Enterobacteriaceae\(^b\) | ≤18 | 19-21 | ≥22 |
| Pseudomonas aeruginosa | ≤19 | 20-22 | ≥23 |
a The current absence of resistant isolates precludes defining any results other than "Susceptible". Isolates yielding results other than "Susceptible" should be submitted to a reference laboratory for further testing.
b E. coli, K. pneumoniae, and E. cloacae only (approved pharmaceutical drug labeling)
# N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
# O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
